This invention relates to performance lighting and, more particularly, to a class of lighting fixture known as the followspot.
Followspots are light projectors designed for changes in beam azimuth, elevation, size, intensity, and generally shape and color, through the agency of a full-time operator, traditionally located next to the fixture and actuating its mechanisms directly by means of control levels projecting through the housing. A description of the Supertrouper followspot, for many years the standard of the industry, may be found in U.S. Pat. No. 2,950,382.
This ability to change beam parameters during a performance has made followspots an invaluable tool in lighting live presentations. Because of their ability to alter azimuth and elevation smoothly during a performance, followspots are uniquely capable of tracking or "following" a moving subject with a beam of light, providing a simple and efficient method of illuminating a performer moving onstage. This adaptability also allows followspots to cope with the unexpected; for example, when a performer stands where no conventional fixture has been aimed. The followspot's ability to alter beam size, shape and color further enhances its usefulness in these roles and allows a single followspot to produce a series of different lighting effects during a performance which might require dozens of conventional fixtures with their attendant support, cabling, dimming, and power requirements to duplicate.
The followspot's benefits have always been mitigated by two major drawbacks: difficulties with control/coordination and the requirement that the operator be located at the fixture itself.
The tasks required of a followspot and its operator include "pickups38 ; presetting the unit's azimuth and elevation with the beam off, so that when it is turned back on, only the desired subject wil be illuminated in a beam of the correct size. This "pickup" may involve either a performer standing at a prearranged location (or "mark") onstage or, in the case of an unrehearsed production, at an unpredictable location. Frequently such "pickups" are complicated by the fact that they must follow a "blackout" when the stage has been plunged into darkness for a scene change or for effect and the subject cannot be seen.
No followspot known in the art has been manufactured with any device to aid the operator in sighting the unit on a subject onstage, not has any followspot in common use provided any device designed to assist in presetting azimuth and elevation to specific settings. The operator can only judge the approximate azimuth and elevation settings and, by extrapolation, beam location onstage, from the position of the housing. After repeated experience with the same followspot in the same location in the same building, an operator may become more adept at guessing the fixture's orientation, and with it, beam location, but this is hardly a satisfactory solution to the problem.
Certain common operations with a followspot (including pickups) require adjustment of the controls for several different beam parameters in a rapid sequence. Yet, no followspot known in the art provides for automatic or semi-automatic coordination between the controls for different parameters.
Furthermore, most productions involve both followspots and conventional lighting fixtures controlled by either a manual preset console (as described in U.S. Pat. No. 3,946,273, for example) or conventional electronic memory system. Although many effects during a performance require synchronized changes in intensity or color involving several followspots, or followspots and the conventional lighting system, no followspot known in the art provides any method of synchronizing such changes. Instead, verbal cues to the separate followspot operators and the console operator who act individually are used--with predictably inconsistent results.
The second major drawback of current followspot designs is the requirement (unchanged since the beginning of the century) that the operator be positioned at the followspot, for it limits the latter to locations that will safely accommodate the former. It has long been apparent to those practicing in the art that considerable benefits would follow if the operator could be located remotely from the followspot itself. The followspot could be placed at the optimal location for lighting and the operator at the optimal location for his safety, efficiency, and comfort without requiring compromise for either. Permanent installations would be spared the cost of followspot booths and platforms; temporary users the present loss of seating and obstructed sightlines. Because it could be consistently located closer to the subject, remote followspots could also employ smaller and less expensive light sources.
Methods for remoting the azimuth, elevation, and beam size adjustment of performance lighting fixtures were first disclosed in the late 1920s in U.S. Pat. No. 1,680,685 and U.S. Pat. No. 1,747,279. Fixtures capable of tracking, and hence remote followspot use, are disclosed in U.S. Pat. No. 2,054,224 and U.S. Pat. No. 3,209,136. Fixtures incorporating such techniques have been prototyped, but in the 50 years since first disclosed, have made no commercial progress, despite the considerable and unique economic advantages that result from relocating the operator of an attended, variable parameter fixture at a location remote from the fixture. (These advantages are also far greater than those of adding both variable parameters and remote operation to conventional, unattended fixtures as was proposed by Izenour in the 1950s and disclosed by von Ballmoos.)
A major obstacle to the practical remote followspot has been the inability of the average operator to approach even his level of performance with an attended one.
One reason is the product of separating operator and followspot. The operator loses even the meager clues to azimuth and elevation the position of its housing provides. It has been maintained, notably in U.S. Pat. No. 2,054,224 that the position of the control lever would provide the same information. It does not for the two reasons described below.
First, the operator, has a very different point-of-view than the fixture, and he is required to convert his control motions from those suggested by the evidence of his own eyes and past experience, to those he calculates will be required from the fixture's point-of-view.
Another problem is that of resolution. At one moment in a performance, a followspot is called upon to sweep across a 60' stage in one continuous motion. A few minutes later, it may have to increment less than 2" to properly center an actor's head in a 12" diameter beam. Such a range of adjustments requires a resolution in excess of 360 parts. When applied to an attended fixture as disclosed in U.S. Pat. No. 2,950,382 with a housing over six feet in length, such resolution is possible in the hands of an experienced operator. When applied to a control lever, as disclosed in U.S. Pat. No. 2,054,224, where the handle moves through an arc of 4" per axis, a lever motion of approximately 0.01" is required for the 2" motion. An accidental lever motion of only 1/16" will cause the beam onstage to jump almost two feet. Such accidental motions are difficult to avoid when the beam must remain stationary for long periods, and even the simple expedient of "clutching out" the control lever during such periods cannot be employed because of the errors it would introduce into the operator's estimation of azimuth and elevation and hence beam position.
It is the object of the present invention to provide methods of solving these difficulties with control and coordination, both for attended and remotely controlled followspots through improved parameter feedback.